Pressure relieved trolley stop for conveyors

ABSTRACT

A stop for conveyors for arresting the forward movement of an article such as a trolley at the time of or after its release from the propelling mechanism of the conveyor. The stop has a member mounted for reciprocal movement into and out of the path of the article. The member includes an article engaging arm and a locking arm and a mechanism for removing the locking arm when the member is to be retracted from article interception position. Removal of the locking arm allows the article engaging arm to shift away from the article in the direction of travel of the article. The article engaging arm is then free to be retracted without interference from the article resulting from the pressure with which the article normally presses against the member.

[451 Aug. 27, 1974 PRESSURE RELIEVED TROLLEY STOP FOR CONVEYORS [75] Inventor: Augusts V. Redlicls, Grand Rapids,

Mich.

[73] Assignee: Rapistan Incorporated, Grand Rapids, Mich.

22 Filed: Sept. 13, 1973 [21] Appl. No.: 396,798

[52] US. Cl. 104/252, 104/172 S, 104/250 [51] Int. Cl B6lk 7/18 [58] Field of Search 104/l72 R, 172 C, 172 S, 104/172 ET, 178, 249, 250, 251, 252; 293/8 Primary Examiner-Lloyd L. King u Assistant Examiner-Randolph A. Reese Attorney, Agent, or FirmPrice, Heneveld, Huizenga & Cooper [57] ABSTRACT A stop for conveyors for arresting the forward movement of an article such as a trolley at the time of or after its release from the propelling mechanism of the conveyor. The stop has a member mounted for reciprocal movement into and out of the path of the article. The member includes an article engaging arm and a locking arm and a mechanism for removing the locking arm when the member is to be retracted from article interception position. Removal of the locking arm allows the article engaging arm to shift away from the article in the direction of travelof the article. The article engaging arm is then free to be'retracted without interference from the article resulting from the pressure with which the article normally presses against the member.

20 Claims, 15 Drawing Figures PATENTEUAUBZYIQH BE? 1 UP 4 FIGI FIG 2 Pmm mumiim 3, 31,528

SHEET 30F 4 FIG IO FIG I2 7 PATENTEI] AUBZ 7 I974 saw am 4% PRESSURE RELIEVED TROLLEY STOP FOR CONVEYORS This invention relates to article stop for conveyors. In

FIG. 2 is a side elevation view of the improved stop;

FIG. 3 is a partially broken plan view of the stop; FIG. 4 is a sectional plan view taken along the plane the following description, it is described as a'stop ap- 5 IV-IV of FIG. 2 showing the stop in extended posiplied to an over and under, power andfree conveyor but, it will be recognized that the invention has utility and is applicable to various other types-of conveyors including in-floor tow line conveyors or as an article arresting device on standard conveyors of the roller, wheel or belt-type. It constitutes an improvement over the type of conveyor stop described in US. Pat. No. 3,347,171 entitled CARRIER STOP AND TRACK HANGER FOR POWER AND FREE CONVEYORS issued Oct. 17, I967 to G. A. Torrance. Conveyor stops of the type disclosed in the Torrance Patent have been known for a number of years and are widely used in the conveyor industry, particularly in the over and under, power and free conveyor systems. Stops of this type have long been recognized as unsatisfactory in that retraction of the stop from active position frequently requires the application of substantial force because the retraction of the stop is resisted by the pressure of the accumulated trolleys or articles which are pressing against it. In the case of conveyors moving large or heavy articles, this line pressure can be very substantial, requiring large and expensive prime movers to withdraw the stop. This makes the stops both expensive and bulky.

SUMMARY OF THE INVENTION The stop of this invention has a tongue which is mounted for reciprocation into and out of the path of articles or trolleys moving along the conveyor. The stop is spring biased into extended position and a prime mover is provided for retracting it. The stop tongue is pivotally mounted at its rearward end whereby its forward or article engaging end is normally free to pivot through a small arc. When the stop reaches its extended position, a bayonet-type slide mechanism is pushed between fixed rollers. The engagement between the bayonet-type slide and the rollers secures the extended, free end of the tongue against pivotal movement about its rearward end. When the stop is to be retracted. the bayonet-type slide is retracted first, thus, releasing the stop tongue to pivot away from the article or trolley pressing against it. Once the tongue is thus freed, the tongue can be retracted with little or no resistance. This permits the use of a small prime mover. Because of the inertia of the stopped articles or trolleys and the speed with which the tongue is retracted, total retraction of the tongue takes place before sufficient forward movement of the article or trolley occurs to reestablish line pressure against the tongue. The mechanism includes lost motion connections such that as the tongue is extended, should the forward movement of the tongue be obstructed, the prime mover and the remaining mechanism can complete its cycle of operation without interference from the blocked tongue and the tongue by the spring bias will be forced to complete its extension movement as soon as the interference has been removed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a fragmentary, generally schematic, side elevation view of a power and free overhead conveyor equipped with this invention;

tion, omitting the drive mechanism and the conveyor track;

FIG. 5 is a sectional elevation view taken along the plane V-V of FIG. 3 showing the stopin extended position;

FIG. 6 is a view similar to FIG. 5 but showing the stop in retracted position;

FIG. 7 is a sectional elevation view taken along the plane VII-VII of FIG. 4;

' FIG. 8 is a sectional elevation view taken along the plane VIIIVIII of FIG. 4;

FIG. 9 is an exploded view of the stop illustrated in FIGS. 1 through 8;

FIG. 10 is a plan view of a modified structure for this invention showing the stop in retracted position;

FIG. 11 is a plan view of the stop shown in FIG. 10 illustrated in extended position;

FIG. 12 is a side elevation view of the locking bayonet of the structure illustrated in FIGS. 10 and 11;

FIG. 13 is an exploded view of the stop mechanism illustrated in FIGS. l0, l1 and 12;

FIG. 14 is a sectional view taken along the plane XIV-XIV of FIG. 10 showing the stop seated in its housing; and

FIG. 15 is a schematic diagram of a control circuit for the stop.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring specifically to FIG. 1, the numeral 10 indicates a power and free, over and under overhead conveyor of conventional construction having a power track 11 positioned above a trolley track 12. The two tracks are aligned and anchored together for cooperative operation by track hangers l3. Travelling within the power track 11 is a driven chain 14 having brackets 15 at spaced intervals. Downwardly depending from the brackets 15 are drive arms 16. The arms 16 are pivotally connected to the brackets 15.

The trolley track provides a guideway and support for carriages 17 which are mounted on spaced pairs of trolleys 18 and 18a. The lead trolley 18 of each of the carriages 17 has a drive dog 19. Since the drive arms 16 are pivotally mounted to the brackets 15 they normally swing down to engage the drive dogs 19 and may be pivoted upwardly to disengage the drive dogs 19 when the forward movement of the carriage 17 is to be arrested.

The chain 14 is preferably equipped with wheels to.

facilitate its movement. In like manner, the trolleys are mounted on wheels 20 which travel in the track 12. All

of this is known structure andis described in detail in copending patent application Ser. No. 244,173 filed Feb. 2, 1972, now US. Pat. No. 3,765,066, entitled IM- PROVED TROLLEY DRIVE FOR OVER AND UNDER CONVEYORS, both inventions being owned by a common assignee.

The stop 30 with which this invention is concerned I drive dog next coming into contact with the stop, thereby halting forward motion of the carriage 17. The direction of movement of the carriages is indicated by the arrow A in FIG. 1.

Referring now to FIG. 2, the stop mechanism includes a pair of spaced base members 31. The base members 31, on one of their ends, are securely attached to and between the track hangers 13. As best seen in FIGS. 8 and 9, each of the base members 31 has an angle 32 secured to it extending lengthwise of the base member and forming a pair of spaced ways. The ways 32 provide support for the generally U-shaped anchor member or channel housing 33. The channel housing is mounted to slide on the ways between the base members 31 on the ways 32. The base members 31, together with the angles 32 form a base frame. As best seen in FIG. 9, the channel housing 33 has a pair of sides 34 and a bottom plate 35. At its forward end, the sides 34 are connected by a cross plate 36. The cross plate 36 is spaced above the bottom 35. The rear end of the channel housing is partially closed by a back plate 37, the lower portion of which depends below the bottom 35 and mounts, on its forward face, a stop pad 38 which is positioned to engage the fixed stops 39 on the ends of the ways 32.

Seated within the channel housing 33 is the stop tongue 40. The stop tongue 40 is substantially narrower than the spacing between the sidewalls 34 of the channel housing and, at its rearward end, is pivotally secured to the channel housing by suitable means such as the fastener 41. The forward end of the stop tongue 40 has a box structure 42. The box structure serves as the trolley engagement means and is provided to insure an adequate area of contact between the trolley and the tongue so that the tongue will not be damaged by the impact resulting from a heavily loaded carriage being abruptly halted when the stop is extended. Mounted in the center of the stop tongue and rearwardly of the box structure 42 is a lock roller 43. The lock roller is preferably mounted in such a way that it may freely rotate for purposes which will be discussed later, although this is not essential to the invention. The lock roller preferably has a smooth, hard surface and is rotatably mounted. Between the lock roller 43 and the opening through which the fastener 41 passes, an elongated slot 44 is provided located on the centerline of the tongue.

Slidably seated on the stop tongue is a locking means or slide 50. The locking slide 50 is an elongated plate and, at its rearward end, has an elongated slot 51 through which the fastener or pin 41 passes. The slot 51 and the fastener 41 together provide a lost motion connection permitting limited forward and rearward movement of the locking slide with respect to the stop tongue, thus, effecting sequential timing of their operation. Depending from the locking tongue is a spring gusset 52.. When the locking tongue is seated on the stop tongue, the spring gusset 52 projects through the slot 44 and through another slot 45 in the bottom of the channel housing 33. The lower end of the spring gusset projects well below the bottom surface of the channel housing 33. The spring gusset 52 secures one end of tension spring 53. The other end of spring 53 is fixed to the cross piece 54 adjacent the forward end of the base members 31.

At the forward end of the locking slide, a pair of locking wedges 55 extend well-forward of the front end of the slide. These wedges are of a hard, indentation resistent material and are secured to the locking slide by any suitable means such as welding- The wedges are spaced apart sufiiciently to form a channel 56 which will slidably receive the locking roller 43. The forward ends of the locking wedges are chamfered toward each other to form a pair of camming surfaces to center the locking roller 43 between the wedges 55. Thus, the wedges form a wedge-shaped cam. Immediately rear- Wardly of the locking wedges 55, a pair of spaced upstanding ears 57 are provided and a control roller 58 is mounted between them. The control roller is spaced a short distance above the top surface of the locking slide.

Projecting below and mounted to the cross plate 36 are a pair of stop rollers 60 (FIGS. 7, 8 and 9). The stop rollers 60 are similar to the lock roller 43 in that they are rotatably mounted and are made of a hard, indentation resistent material having a smooth surface. The spacing of the stop rollers 60 is such that the locking wedges 55 will pass between them and, thus, as indicated in FIG. 7, the locking wedges will form a body bridging and occupying the space between the locking roller 43 and the stop rollers 60 as indicated in FIG. 7.

Mounted to the track hanger l3 and extending laterally away from the conveyor above the base 31 is a mounting bracket 70. The mounting bracket is rigidly secured to the track hangers and, at its outward end, pivotally mounts the upper end of an actuating lever 71 (FIG. 2). The lower end of the actuating lever 71 is of reduced width forming a finger 72 which engages the forward face of the control roller 58. Spaced from both the pivotal mounting of the actuating lever and the fingers 72, a drive bar 74 is pivotally connected to the actuating-lever. The drive bar is slotted at 75 to provide a lost motion connection with the bolt 76 connecting it to the lever 71. The length of the slot 75 is such that thelever 71 may move through its entire arc of actuating movement without the bolt 76 binding with either end of the slot 75.

At its rearward end, the drive bar 74 is rotatably connected to the eccentric 77 which, in turn, is eccentrically mounted on the drive shaft 78. Thus, the lever 71 and drive bar 74 form a connecting linkage between the eccentric and the locking slide. The eccentric 77, in the preferred form, is substantially triangular in shape with the shaft mounted adjacent one apex and one side of the triangle forming a cam surface 79. Mounted on the drive assembly are a pair of microswitches M 1 and M2. The actuator arms for the microswitches M1 and M2 are so spaced and positioned that each of them are actuated by the cam surface 79 as the eccentric 77 is rotated.

The eccentric 77, shaft 78 as well as the switches M1 and M2 aremounted on the drive assembly housing 80 (FIG. 3). Inside the housing is a speed reducer 81 connected to a prime mover 82. The shaft 78 is connected to the speed reducer. The prime mover 82 can be a fractional horsepower electric motor, since the only energy demand upon it is that necessary to withdraw the tongue 40 from between the locking rollers when the stop is subject to line pressure from the carriages and also against the bias of the spring 53 as will be explained more fully under Operation. Other types of small prime movers can be used without departing from the principles of this invention.

A brake 85 is also provided to positively stop the movement of the eccentric. The brake, in one form can be spring biased into braking action and deactivated by a solenoid 86 connected to the circuit for the motor 82. Various other arrangements can be used to control the actuation of the brake. Further description of the brake is not given, since brakes of this type are conventional commercial products.

Preferably, an adjustable connection 83 provides means of adjusting the exact forward and rearward position of the drive bar 74 so that it will permit full extension of the stop tongue 40 when the stop is extended.

MODIFIED CONSTRUCTION FIGS. through 14 illustrate a modified stop 30a.

In this arrangement, the same spaced base members 31 are utilized. Ways 320, similar to the ways 32 are attached to the base members forms a base frame differing only in that the horizontal flanges are longer (FIG. 14). Seated on the ways 32a is a stop arm 102 and a holding arm 103. The rearward ends of the arms 102 and 103 are received into and secured to the anchor member or channel 104 at the pivots 105 and 105a. The forward end of the stop arm 102 has a box-like structure 106 similar to the box 42 on the end of the stop tongue 40. It is provided for the same purpose. The holding arm 103 is shorter than the stop arm 102 and has no box structure at its forward end. It will be noted that the box portion 106 of the stop arm 102 is generally L-shaped and the holding arm 103 fits within the pocket created by the enlarged forward end of the stop arm I02.

Adjacent the forward end of the holding arm 103 is a locking roller 107. A similar locking roller 107a is mounted on the stop arm 102 at the same spacing from the pivots 105 and 105a. The locking rollers 107 and 107a are preferably rotatably mounted and of the same material as the stop rollers 60. Thus, they are similar both in structure and in purpose to the stop rollers 60 illustrated in FIG. 7.

The arms 102 and 103 are channel-shaped with their open sides facing toward each other. They are spaced to form a slot 108 between them. Seated within the arms 102 and 103 and centered with respect to the slot 108 is a bayonet slide 109. The bayonet slide consists of a pair of spaced side bars 110 joined at their rearward ends by a pusher plate 111 and a depending spring gusset 112. The spring gusset secures a tension spring 117 (FIG. 14), the forward end of which is attached to a cross bar extending between the base members 31 in a manner identical to that illustrated and described for the construction shown in FIGS. 1 through 9. The spring 117 serves the same function as the spring The forward end of the bayonet slide has a laterally extending projection bar 113 rigidly secured to the side bars 110. Forwardly of the projection bar 113, a bayonet cam 114 of hardened, indentation resistent material is provided. The forward end of the bayonet cam is chamfered to form a point and the cam, itself, has a maximum width equal to the spacing between the rollers 107 and 107a when the anns 102 and 103 are fully separated. Approximately midway between the pusher plate 111 and the projection bar 113, a roller 115 is rotatably mounted between the side bars 110. The roller stop pad 12] serves the same purpose as the stop pad 38 in the preferred construction and, at the limit of ex tension travel of the unit, it engages the stops 122 (FIG. 14

OPERATION The operation of both the preferred and the modified embodiments of this invention are quite similar. The operation of the preferred embodiment shown in FIGS. 1 through 9 will be described first.

Referring to FIG. 1, it is assumed that the conveyor is being operated in the direction of the arrow A. When the lead carriage 17 reaches the stop 30, the stop will first engage the cam surface 16a on the forward face of the drive arm 16 lifting it and causing it to disengage the drive dog 19. At this point, the carriage is free and continues to move only because of its momentum. Almost immediately after the disengagement of the drive arm 16, the drive dog 19 will engage the stop. This will stop further forward movement of the carriage 17.

Prior to the approach of the carriage 17, the stop will have been shifted to extended position, i.e., the position illustrated in FIGS. 2, 3, 4, and 5. To extend the stop to this position, a signal will have been generated from any suitable source, either automatic or manual, which will cause the circuit interrupt produced by micro-switch M1 to be bypassed, energizing the prime mover 82. This will cause the shaft 78 to rotate along with the eccentric 77. As the eccentric rotates from its original position in contact with the micro-switch M1 to the position illustrated in FIG. 2, the drive bar 74 will shift forwardly or to the left, as illustrated in FIG. 2. As the drive bar 74 shifts forwardly, the bias of the spring 53 will pull the locking slide forwardly. During the initial portion of forward movement of the locking slide, only the locking slide 50 will move since the fastener 41 will have been at the forward end of the slot 51 (FIG. 6). However, when the locking slide 50 has shifted forward sufficiently that the fastener 41 engages the rear end of the slot 51 in the locking slide, forward motion of the stop tongue and the channel housing 33 will be initiated. This motion will continue until the stop pad 38 engages the stops 39 on the rear ends of the ways 32. At this point, the stop tongue 40 is-fully extended.

During the initial forward movement of the locking slide 50, the locking wedges will be shifted forwardly and will pass between the locking roller 43 and the stop rollers to create the condition illustrated in FIG. 7. At this point, the forward end of the stop tongue 40 is firmly held against any pivotal movement with respect to the channel housing 33 and, in turn, the channel housing 33-is held against pivotal movement because itfits closely between the stationary frame members 31. Since the lock roller 43 and the stop rollers 60 have low friction surfaces, this sliding of the wedges 55 between them will require little energy and there will be no tendency to retard the forward motion of the locking slide.

It will be seen that since the extension or forward movement of the locking tongue 40 is effected solely by the spring 53 that the drive bar 74 serves only as a retarder and not as a drive for the locking tongue. Should, for any reason, the forward motion of the locking tongue be obstructed such as the unit being actuated while one of the trolleys 18 is in front of the locking tongue, the prime mover 82 and its connected drive arm 74 are free to continue through their full cycle of forward movement since all that will happen is that the actuating lever 71 and the tongue will remain stationary while the bolt 76 slides along the lost motion slot 75. This arrangement is important in protecting from injury the drive mechanism for the eccentric 77, permitting it to complete its operating cycle.

When the drive bar 74 has reached its fully extended position, irrespective of whether the locking tongue has been able to also reach its fully extended position, the cam surface 79 on the eccentric 77 will engage the micro-switch M2 interrupting power to the prime mover 82. Once extended, the stop will remain in this condition until a retraction signal is given.

When the retraction signal is given, the prime mover 82 is again energized rotating the eccentric 77 180. The rotation of the eccentric 77 pulls the actuator lever 71 to the right against the bias of the spring 53. The first segment of movement of the actuator arm 71 causes the locking slide 50 to shift rearwardly without moving any of the other components of the stop. This action occurs because of the lost motion connection provided by the slot 51. This retraction or movement to the right of the locking slide (as illustrated) is sufficient to withdraw the wedges 55 from between the stop rollers 60 and from around the lock roller 43. As soon as this happens, the stop tongue 40 is unlocked and will immediately shift away from the carriage pressing against it. Simultaneously, the fastener 41 will engage the front or left-hand end of the slot 51 and thereafter the stop tongue 40 and the housing channel 33 will also shift to the right or retract. This withdraws the stop tongue 40 from the path of the carriages. The rotatable mounting of the stop rollers 60 and the lock roller 43 greatly facilitate the extension and retraction of the wedges 55, reducing energy requirements to a minimum. Both the wedges and these rollers must be of a hard material, preferably hardened steelto prevent indentation resulting from line pressure by the carriages.

This retraction movement is completed quickly enough that the tongue will be entirely withdrawn from the path of the carriage before the inertia of the carriage is overcome and the carriage moves forwardly on the conveyor track to a point where it would once again, engage the tongue. The retraction of the stop is terminated when the cam surface 79 of the eccentric 77 actuates the switch Ml. It is obvious from this description that it is important that the length of the slot 51 be such that the wedges are first moved into fully locked position between the stop rollers 60 and about the locking roller 43 before extension or forward movement of the locking tongue 40 is initiated and that the same wedges are fully withdrawn from between the same rollers before retraction movement of the tongue 40 is initiated. This is important on the extension movement because should the wedges not be fully extended and the tongue engaged by a carriage, the side pressure resulting from impact between the carriage and the end of the tongue could cause the mechanism to jam. On retraction, failure to fully release the tongue from the locking action of the wedges 55 would frustrate the purpose of the mechanism by attempting to withdraw the tongue before it is free to pivot into carriage disengaging position.

FIG. 15 illustrates a control system suitable for regulating the operation of the prime mover 82. The source of electrical power indicated as line is provided with a switch 200. Assuming that the stop is in fully extended position, the switch 200 is shifted to the right to close the line 201 connected to the micro-switch M 1. This will energize the motor 82 through line 202 since both switches M1 and M2 are closed to this line. When the eccentric 77 engages the switch Ml, it will be shifted to open line 202 and energize line 203. The operation of the prime mover 82 will cease since the M2 switch will remain closed to line 202 and not to line 203. In this condition the stop is retracted.

The next time the stop is to be operated, the switch 200 is shifted over to close line 204 thus energizing the motor through line 202 and switch M2. This condition will continue until the eccentric 77 actuates switch M2 opening line 202 and closing the circuit to line 203. The motor at this point will stop since the switch Ml has previously been switched to connect lines 201 and 203 but the switch 200 is open with respect to line 201. The stop is now fully extended. It will be obvious that to initiate the next full cycle, the switch 200 is restored to its original position shown in FIG. 15 which will energize the motor through lines 201 and 203 and the switch M1.

Operation of the switch 200 may be either automatic or manual. Either system is conventional in the conveyor art and forms no part of this invention. Therefore, the means for operating switch 200 is neither illustrated nor described in further detail.

It will be recognized that in the construction shown in FIGS. 1 through 9, it is irrelevant from which direction the carriages apply line pressure to the tongue 40. This is true because the tongue is free to pivot either to the right or to the left, once the locking wedges 55 have been retracted. Thus, the stop may be mounted on either side of the conveyor track and, it is irrelevant from which direction the carriages 17 approach. In this manner, the stop illustrated in FIGS. 1 through 9 differs from the stop illustrated in FIGS. 10 through 14. The stop in these later figures is effective only for carriages approaching in the direction of the arrow A, as the stop is illustrated in FIG. 13. Thus, if the modified stop is to be used on a conveyor on which the carriages would be approaching from the opposite direction, the stop mechanism must be mounted on the other side of the conveyor.

The operation of the stop shown in FIGS. 10 through 14 is very similar to that of the stop illustrated in FIGS. 1 through 9. When this stop is in extended position, the bayonet slide 109 is shifted to its maximum forward position. In this position, the bayonet cam is thrust between the rollers 107 and 107a, forcing them apart and, thus, holding the stop arm 102 in its maximum upstream position with respect to the direction of movement of the carriages along the conveyor. Carriages pressing against the stopv in the direction of arrow A (FIG. 13) force the holding arm 103 against the adjacent base member, thus, providing a positive support for the stop arm 102. Once against the rotatable mounting of the rollers 107 and 1070 and the fact that both the rollers and the bayonet slide 109 are of hardened material greatly facilitates the unit's actuation.

The modified stop is actuated by the same lever, drive bar, eccentric and controls as that shown and described for the preferred embodiment. The actuator lever bears against the forward face of the roller 115. To retract the stop, the actuating lever is shifted to the right as the stop is illustrated in FIGS. 10 through 13. It will be noted from FIG. 10 that in the extended position, the pusher plate 111 is spaced forwardly from the channel 104. This provides a lost motion arrangement permitting the bayonet slide 109 to be withdrawn rearwardly sufficiently to retract the bayonet cam 114 from between the rollers 107 and 107a. At this point, the extended or free end of the stop arm 102 is free to pivot away from the carriages thus releasing it from line pressure. This shift toward the holding arm 103 is illustrated in P16. 10. Also, at this point, the pusher plate 111 will engage the channel 104 and continued motion of the actuating lever will now retract the entire stop assembly from the path of the carriages.

To extend the stop again, the actuating lever is caused to move to the left as the stop mechanism is illustrated in FIGS. 10 through 13. The initial portion of this movement will force the bayonet cam 115 between the rollers 107 and 107a thus creating the lock between the arms 102 and 103. Continued forward movement of the bayonet slide 109 will bring the projection bar 113 into engagement with the rollers 107 and 107a. Thereafter, the entire stop mechanism will be pushed into extended position until the stop pad 121 engages the stops 122 on the base members 31. Once again, it will be recognized that the extension of the stop results from the bias of the spring 117 and thus the actuating lever 71 merely serves to regulate the rate of extension. It will also be recognized that should the extension of the stop be obstructed that this will not prevent the prime mover 82 and its connected structure from completing its cycle of movement between the switches M1 and M2. It will also be recognized that since the line pressure has been removed from the stop beforeretraction is initiated, the only energy demand on the prime mover 82 is that sufficient to overcome the bias of the spring 117.

The invention provides a positive stop mechanism which has eliminated the necessity for large bulky heavy duty prime movers in order to retract the stop. It also provides a stop mechanism which will be comparatively quiet in operation and durable because it is not possible to damage the driving mechanism as a result of obstruction in the path of the extension movement of the stop. By eliminating the necessity of forcibly pulling the stop from in front of the carriages while the stop is subjected to full line pressure not only are the forces which must be overcome greatly reduced, but also the wear on the mechanism is significantly reduced and many of the operating components can be lighter in weight and less massive. The reduction in cost is quite significant in large conveyor installations since a number of these stops are frequently used, thus multiplying the savings.

It will be recognized that while this invention has been specifically described as applied to an overhead conveyor, it could as readily be applied to an in-floor conveyor or to a conventional roller or wheel conveyor as an article stop with modifications which are wholly routine and do not, in any way, depart from the principles of this invention.

While a preferred and a modified construction of this invention have been described, it will become apparent to those skilled in the art that other modifications of this stop can be made, both to the physical structure and to the control and prime mover for the stop without departing from the spirit or the scope of the present invention as defined by the hereinafter appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

1. A stop for conveyors, said stop having an article engaging tongue, means mounting said tongue both for lateral movement and for reciprocation between extended article engaging and retracted article disengaging positions; locking means movable between locked and unlocked positions; said locking means in locked position engaging said tongue and holding said tongue against lateral movement and in unlocked position disengaging said tongue; means for shifting said locking means into locked position as said tongue is shifted to extended position and for shifting said locking means into unlocked position before said tongue is retracted whereby said tongue may shift laterally before said tongue is retracted.

2. A stop for conveyors as described in claim 1 further characterized in that a lost motion connection is provided between said locking means and said tongue for effecting sequential shifting of said locking means and said tongue.

3. A stop for conveyors as described in claim 2 further characterized in that said means for shifting said locking means includes a spring for biasing said locking means and tongue into extended position and a prime mover for shifting said locking means and tongue into retracted position.

4. A stop for conveyors, said stop having an article engaging tongue, said tongue having a forward article engaging end and a rearward end; means mounting said tongue both for lateral pivotal movement of said forward end and for reciprocation between extended article engaging and retracted article disengaging positions; locking means movable between locked and unlocked positions; said locking means in locked position engaging said tongue and holding said forward end thereof against pivotal movement and in unlocked position disengaging said tongue; means for shifting said locking means into locked position as said tongue is shifted to extended position and for shifting said locking means into unlocked position before said tongue is retracted whereby said tongue may pivot before said tongue is retracted.

5. A stop for conveyors, said stop having a base frame and an anchor member mounted thereon for reciprocal movement, a tongue mounted on said anchor member for reciprocal movement between extended and retracted positions, the forward end of said tongue in extended position being adapted to engage and arrest articles on the conveyor, said stop characterized in that means are provided for securing the rearward end of said tongueto said anchor frame' for pivotal movement laterally thereof; lock means shiftable between locked and unlocked positions; means connected to said lock means for shifting said lock means between its positions and means for reciprocating said tongue; means for sequentially timing the operation of said lock means and said tongue whereby said lock means is shifted into locked position before said tongue is shifted to extended position and said lock means is shifted to unlocked position before said tongue is shifted to retracted position; said lock means in locked position holding said tongue against lateral pivotal movement.

6. A stop for conveyors as described in claim further characterized in that a first lock means engaging member is mounted on said tongue and a second lock engaging member is fixedly secured to said anchor member; said lock means in locked position being seated between said first and second members for holding said tongue and said first member against movement toward said second member.

7. A stop for conveyors as described in claim 6 further characterized in that said lock means has a forward portion, said portion being wedge-shaped to cam said first and second members apart.

8. A stop for conveyors as described in claim 7 further characterized in that said first and second members are rotatably mounted and are of hardened, indentation resistent material having a low coeffecient of friction surface to facilitate the engagement and disengagement of said forward end of said lock means.

9. A stop for conveyors as described in claim 5 further characterized in that a first lock means engaging member is mounted on said tongue and a pair of second lock engaging members are fixedly secured to said anchor member, said second locking engaging members being spaced apart laterally of said anchor member whereby said first lock engaging member can pass between them; said lock means having a pair of arms forming a bifurcated cam portion, said arms, when said lock is in locked position receiving said first lock member between them and engaging both of said second lock members for holding said tongue and first lock member against lateral pivotal movement; said arms when said lock means is in unlocked position being disengaged from both said first and second members.

10. A stop for conveyors as described in claim 5 further characterized in that said lock means is a plate seated upon said tongue and slidable lengthwise thereof; said plate having a slot elongated lengthwise thereof for receiving therethrough said means securing the rearward end of said tongue, the length of said slot being such as to permit said plate limited movement relative to and lengthwise of said tongue; means resiliently biasing said plate forwardly toward locked position; a prime mover and means connecting said prime mover to said plate for restraining said plate against forward movement; control means for said prime mover intermittently actuating said prime mover to alternately shift said connecting means between tongue extended and tongue retracted positions.

11. A stop for conveyors as described in claim 10 further characterizedin that said securing means is a pin and plate shifts said tongue into extended position after the rearward end of said slot engages said pin and said plate has shifted in locked position and said plate shifts said tongue into retracted position after the forward end of said slot engages said pin and said plate has shifted into unlocked position.

l2. A stop for conveyors as described in claim 11 further characterized in that said connecting means in a linkage one end of which engages said plate; said linkage having a lost motion connection permitting said linkage to shift to tongue extended position without corresponding movement of said plate on said tongue.

13. A stop for conveyors as described in claim 12 wherein said prime mover is an electric motor; a cam operatively connected to and rotated by said motor; said linkage having a drive bar and a control link; one end of said control link being pivotally mounted and the other end thereof engaging said plate; said lost motion connection being between said drive bar and said control link.

14. A stop for conveyors as described in claim 13 wherein a pair of switches are provided in the electrical supply for said motor; said switches being mounted for alternate actuation by said cam, one when said tongue is in extended position and the other when said tongue is in retracted position.

15. A stop for conveyors, said stop having a base frame and an anchor member mounted thereon for reciprocal movement, a tongue mounted on said anchor member for reciprocal movement between extended and retracted positions, the forward end of said tongue in extended position being adapted to engage and arrest articles on the conveyor, said stop characterized in that said tongue having a stop arm and a holding arm, lock means seated between said arms; said lock means being movable lengthwise with respect to said arms between a locked position and an unlocked position, said lock means in locked position holding said stop and holding arms apart and in unlocked position releasing said stop arm for pivotal movement toward said holding arm, means for sequentially shifting said lock means into locked position and then said tongue into extended position and for sequentially shifting said lock means into unlocked position and then said tongue into retracted position.

16. A stop for conveyors as described in claim 15 wherein a lost motion connection is provided between said lock means and said tongue for effecting said sequential operation.

17. A stop for conveyors as described in claim 16 wherein a lock engaging member if fixedly secured to each of said stop and holding arms and said lock means has a bayonet portion mounted thereon for travel between and engagement of said lock engaging members; a bar on said lock means rearwardly of said bayonet portion engageable with said lock engaging means for shifting said tongue into extended position after said bayonet has engaged said lock engaging means.

18. A stop for conveyors as described in claim 17 wherein said shifting means includes a spring secured to said lock means for resiliently biasing said lock means into locked position and said tongue into extended position and a prime mover and linkage connected to said lock means for retracting both said lock means and said tongue against the bias of said spring.

19. A stop for conveyors, said stop having a tongue and means for reciprocating said tongue between extended and retracted positions, said tongue in extended position projecting into the path of articles on the conveyor and restraining their forward movement, the imconveyor; lock means for pivoting said tongue into an upstream position with respect to the direction of movement of articles on the conveyor and locking said tongue against pivotal movement when said tongue is in extended position; means for sequentially disengaging said lock means to free said tongue for pivotal movement and retracting said tongue.

20. In combination, a conveyor having an article supporting track along which articles are transported and a stop, said stop having a tongue and means for reciprocating said tongue between extended and retracted positions, said tongue in extended position projecting into the path of articles moving along said track and in retracted position being withdrawn from said track, said combination characterized in that means are secured to said conveyor for mounting said tongue both for lateral movement and for reciprocation between extended and retracted positions; locking means movable between locked and unlocked positions, said locking means in locked position engaging said tongue and holding said tongue against lateral movement in the direction of movement of articles on said track, and in unlocked position disengaging said tongue and fixing it for lateral movement; means for shifting said locking means into locked position and then shifting said tongue into extended position and for shifting said locking means into unlocked position then retracting said tongue whereby said tongue can disengage articles on said track before it is retracted. 

1. A stop for conveyors, said stop having an article engaging tongue, means mounting said tongue both for lateral movement and for reciprocation between extended article engaging and retracted article disengaging positions; locking means movable between locked and unlocked positions; said locking means in locked position engaging said tongue and holding said tongue against lateral movement and in unlocked position disengaging said tongue; means for shifting said locking means into locked position as said tongue is shifted to extended position and for shifting said locking means into unlocked position before said tongue is retracted whereby said tongue may shift laterally before said tongue is retracted.
 2. A stop for conveyors as described in claim 1 further characterized in that a lost motion connection is provided between said locking means and said tongue for effecting sequential shifting of said locking means and said tongue.
 3. A stop for conveyors as described in claim 2 further characterized in that said means for shifting said locking means includes a spring for biasing said locking means and tongue into extended position and a prime mover for shifting said locking means and tongue into retracted position.
 4. A stop for conveyors, said stop having an article engaging tongue, said tongue having a forward article engaging end and a rearward end; means mounting said tongue both for lateral pivotal movement of said forward end and for reciprocation between extended article engaging and retracted article disengaging positions; locking means movable between locked and unlocked positions; said locking means in locked position engaging said tongue and holding said forward end thereof against pivotal movement and in unlocked position disengaging said tongue; means for shifting said locking means into locked position as said tongue is shifted to extended position and for shifting said locking means into unlocked position before said tongue is retracted whereby said tongue may pivot before said tongue is retracted.
 5. A stop for conveyors, said stop having a base frame and an anchor member mounted thereon for reciprocal movement, a tongue mounted on said anchor member for reciprocal movement between extended and retracted positions, the forward end of said tongue in extended position being adapted to engage and arrest articles on the conveyor, said stop characterized in that means are provided for securing the rearward end of said tongue to said anchor frame for pivotal movement laterally thereof; lock means shiftable between locked and unlocked positions; means connected to said lock means for shifting said lock means between its positions and means for reciprocating said tongue; means for sequentially timing the operation of said lock means and said tongue whereby said lock means is shifted into locked position before said tongue is shifted to extended position and said lock means is shifted to unlocked position before said tongue is shifted to retracted position; said lock means in locked position holding said tongue against lateral pivotal movement.
 6. A stop for conveyors as described in claim 5 further characterized in that a first lock means engaging member is mounted on said tongue and a second lock engaging member is fixedly secured to said anchor member; said lock means in locked position being seated between said first and second members for holding said tongue and said first member against movement toward said second member.
 7. A stop for conveyors as described In claim 6 further characterized in that said lock means has a forward portion, said portion being wedge-shaped to cam said first and second members apart.
 8. A stop for conveyors as described in claim 7 further characterized in that said first and second members are rotatably mounted and are of hardened, indentation resistent material having a low coeffecient of friction surface to facilitate the engagement and disengagement of said forward end of said lock means.
 9. A stop for conveyors as described in claim 5 further characterized in that a first lock means engaging member is mounted on said tongue and a pair of second lock engaging members are fixedly secured to said anchor member, said second locking engaging members being spaced apart laterally of said anchor member whereby said first lock engaging member can pass between them; said lock means having a pair of arms forming a bifurcated cam portion, said arms, when said lock is in locked position receiving said first lock member between them and engaging both of said second lock members for holding said tongue and first lock member against lateral pivotal movement; said arms when said lock means is in unlocked position being disengaged from both said first and second members.
 10. A stop for conveyors as described in claim 5 further characterized in that said lock means is a plate seated upon said tongue and slidable lengthwise thereof; said plate having a slot elongated lengthwise thereof for receiving therethrough said means securing the rearward end of said tongue, the length of said slot being such as to permit said plate limited movement relative to and lengthwise of said tongue; means resiliently biasing said plate forwardly toward locked position; a prime mover and means connecting said prime mover to said plate for restraining said plate against forward movement; control means for said prime mover intermittently actuating said prime mover to alternately shift said connecting means between tongue extended and tongue retracted positions.
 11. A stop for conveyors as described in claim 10 further characterized in that said securing means is a pin and plate shifts said tongue into extended position after the rearward end of said slot engages said pin and said plate has shifted in locked position and said plate shifts said tongue into retracted position after the forward end of said slot engages said pin and said plate has shifted into unlocked position.
 12. A stop for conveyors as described in claim 11 further characterized in that said connecting means in a linkage one end of which engages said plate; said linkage having a lost motion connection permitting said linkage to shift to tongue extended position without corresponding movement of said plate on said tongue.
 13. A stop for conveyors as described in claim 12 wherein said prime mover is an electric motor; a cam operatively connected to and rotated by said motor; said linkage having a drive bar and a control link; one end of said control link being pivotally mounted and the other end thereof engaging said plate; said lost motion connection being between said drive bar and said control link.
 14. A stop for conveyors as described in claim 13 wherein a pair of switches are provided in the electrical supply for said motor; said switches being mounted for alternate actuation by said cam, one when said tongue is in extended position and the other when said tongue is in retracted position.
 15. A stop for conveyors, said stop having a base frame and an anchor member mounted thereon for reciprocal movement, a tongue mounted on said anchor member for reciprocal movement between extended and retracted positions, the forward end of said tongue in extended position being adapted to engage and arrest articles on the conveyor, said stop characterized in that said tongue having a stop arm and a holding arm, lock means seated between said arms; said lock means being movable lengthwise with respect to said arms between a locked position and an unlocked posiTion, said lock means in locked position holding said stop and holding arms apart and in unlocked position releasing said stop arm for pivotal movement toward said holding arm, means for sequentially shifting said lock means into locked position and then said tongue into extended position and for sequentially shifting said lock means into unlocked position and then said tongue into retracted position.
 16. A stop for conveyors as described in claim 15 wherein a lost motion connection is provided between said lock means and said tongue for effecting said sequential operation.
 17. A stop for conveyors as described in claim 16 wherein a lock engaging member if fixedly secured to each of said stop and holding arms and said lock means has a bayonet portion mounted thereon for travel between and engagement of said lock engaging members; a bar on said lock means rearwardly of said bayonet portion engageable with said lock engaging means for shifting said tongue into extended position after said bayonet has engaged said lock engaging means.
 18. A stop for conveyors as described in claim 17 wherein said shifting means includes a spring secured to said lock means for resiliently biasing said lock means into locked position and said tongue into extended position and a prime mover and linkage connected to said lock means for retracting both said lock means and said tongue against the bias of said spring.
 19. A stop for conveyors, said stop having a tongue and means for reciprocating said tongue between extended and retracted positions, said tongue in extended position projecting into the path of articles on the conveyor and restraining their forward movement, the improvement in said stop comprising: said tongue having a forward end and a rearward end, said forward end being the article engaging portion thereof; a pivot member pivotally mounting the rearward end of said tongue whereby the forward end of said tongue can shift in the direction of movement of articles on the conveyor; lock means for pivoting said tongue into an upstream position with respect to the direction of movement of articles on the conveyor and locking said tongue against pivotal movement when said tongue is in extended position; means for sequentially disengaging said lock means to free said tongue for pivotal movement and retracting said tongue.
 20. In combination, a conveyor having an article supporting track along which articles are transported and a stop, said stop having a tongue and means for reciprocating said tongue between extended and retracted positions, said tongue in extended position projecting into the path of articles moving along said track and in retracted position being withdrawn from said track, said combination characterized in that means are secured to said conveyor for mounting said tongue both for lateral movement and for reciprocation between extended and retracted positions; locking means movable between locked and unlocked positions, said locking means in locked position engaging said tongue and holding said tongue against lateral movement in the direction of movement of articles on said track, and in unlocked position disengaging said tongue and fixing it for lateral movement; means for shifting said locking means into locked position and then shifting said tongue into extended position and for shifting said locking means into unlocked position then retracting said tongue whereby said tongue can disengage articles on said track before it is retracted. 